title: Prolactin induced tyrosine phosphorylation of p59fyn may mediate phosphatidylinositol 3-kinase activation in Nb2 cells.
abstract: Our previous studies indicated that PI3-kinase is involved in prolactin (PRL) signalling. We have now examined the involvement of the src tyrosine kinase, fyn, in PRL-induced the activation of PI3-kinase in the rat lymphoma cell line, Nb2. Cells were stimulated with increasing doses of PRL, lysed and immunoprecipitated with anti-fyn specific antibody. Then PI3-kinase activity was measured as the increase in the phosphorylation of phosphatidylinositol to phosphatidylinositol 3-phosphate separated by TLC. Our data indicated that, in PRL treated cells, co-precipitation of PI3-kinase with anti-fyn antiserum led to time and dose-dependent activation of PI3-kinase in vitro and that this activation was blocked by the addition of LY294002. However, LY294002 appeared to have no effect on fyn autophosphorylation. Furthermore, the physical association of PI3-kinase with fyn was confirmed by Western blot analysis employing the same specific antisera. These data provide evidence that PRL-induced activation of PI3-kinase may be mediated by the tyrosine phosphorylation of fyn in Nb2 cells.
authors.affiliation: Cellular Signalling Section, University of Sheffield Medical School, UK.
authors.forename: K A
authors.initials: KA
authors.lastname: al-Sakkaf
authors.forename: P R
authors.initials: PR
authors.lastname: Dobson
authors.forename: B L
authors.initials: BL
authors.lastname: Brown
mesh_terms: D002867:Chromones / Q000494:pharmacology; D002934:Cinnamates / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D009025:Morpholines / Q000494:pharmacology; D019869:Phosphatidylinositol 3-Kinases / Q000187:drug effects* / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation / Q000187:drug effects; D011233:Precipitin Tests; D011388:Prolactin / Q000008:administration & dosage / Q000494:pharmacology*; D011518:Proto-Oncogene Proteins / Q000187:drug effects* / Q000378:metabolism*; D051076:Proto-Oncogene Proteins c-fyn; D013997:Time Factors; D014407:Tumor Cells, Cultured; D014443:Tyrosine / Q000187:drug effects / Q000378:metabolism*
chemical_list: D002867:Chromones; D002934:Cinnamates; D004791:Enzyme Inhibitors; D009025:Morpholines; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011388:Prolactin; D011518:Proto-Oncogene Proteins; D051076:Proto-Oncogene Proteins c-fyn; D014443:Tyrosine; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one